Subgap structure in the conductance of a three-terminal Josephson junction

Abstract

Three-terminal superconductor (S) -normal metal (N) -superconductor (S) Josephson junctions are investigated. In a geometry where a T-shape normal metal is connected to three superconducting reservoirs, new sub-gap structures appear in the differential resistance for specific combinations of the superconductor chemical potentials. Those correspond to a correlated motion of Cooper pairs within the device that persist well above the Thouless energy and is consistent with the prediction of quartets formed by two entangled Cooper pairs. A simplified nonequilibrium Keldysh Green's function calculation is presented that supports this interpretation.

Topological transconductance quantization in a four-terminal Josephson junction

“…At lower voltages, 0.1 /e V 2 /e, we observe a complex dependence of the direct conductances as well as the transconductances, with resonant features that are related with multiple Andreev reflections involving various leads [28][29][30][31][32][33].…”

A ballistic two-dimensional-electron-gas Andreev interferometer

“…Up to now, most of the related experimental works have been focused on the study of hybrid devices based on diffusive semiconductor nanowires 9,10 , normal metals 5,6 and ferromagnets 7 . Nevertheless, the structure flexibility and the reduced influence of disorder candidate S-2DEG systems as a promising platform to reach the complete understanding of these effects 11,12 .…”

“…The combination of ballistic two-dimensional-electrongases (2DEGs) and superconductors (S) may represent a key tool for the investigation of Majorana bound states 1-4 , the generation of solid-state entanglers 5,6 as well as spin triplet superconductivity 7,8 . Up to now, most of the related experimental works have been focused on the study of hybrid devices based on diffusive semiconductor nanowires 9,10 , normal metals 5,6 and ferromagnets 7 .…”

Quartets and the current-phase structure of a double quantum dot superconducting bijunction at equilibrium

“…This understanding of the CPR should clarify the nature of the nonequilibrium transport, which offers new coherent dc channels in presence of applied voltages, provided the latter are commensurate [6,9,13], and also nonlocal multiple Andreev incoherent channels [7,8]. Subgap anomalies in a diffusive Al-Cu bijunction have indeed been recently observed and interpreted in terms of quartets (see Figure 8b) [14]. Notice that a related set-up has been proposed in the context of Majorana fermion physics [37].…”

“…The present work focuses on the ABS structure at equilibrium of a tri-terminal Josephson [6][7][8][9][10][11][12][13][14]. It elucidates its current-phase relation as a function of the two phase variables, hence the name "bijunction".…”